Posted: Mon Jan 22, 2007 8:00 pm Post subject: Building a 350 for a friend and had cam questions.

I am going to use a hydraulic roller and wanted to see if there is any input to be given. The motor is a 97 4 bolt 350 with K/B hyper flat tops. The heads are Super Comp aluminum CNC 195 cc intake that have a very good combustion chamber design like the LT1 and fast burn. Chambers are 64 cc. The Motor is in a S10 and probably weighs less than 3500#. He has an Edelbrock speed density EFI that he is running and will run with the new motor.

I was looking at the Ram Jet cam# 14097395. The cam seems pretty small but the Ram Jet makes supposedly 350 HP at 5200. If the LT1 has a different street able cam available I would appreciate the input.

Camshaft (14097395) roller cam. Lift is .431/.451, duration @ .050 is 196/206 and 112° LSA is one set of specs I have found. Looks like it may have a 108 intake centerline. (I've also seen 114° LSA).

I would think you should be able to run up to about 230° @ 0.050" 112° lobe separation angle with a chip rethink. The speed density should be able to handle the increased air volume but I would question the service duty cycles on the injectors unless they are in the 45-48 lbs. range. Though I am only vaguely aware of the EFI aspect, and have always been on the outside looking in.

The ZZ4 cam is a good bit bigger yet completely well mannered and makes 355hp with L98 heads which flow 15% less than the Vortecs.

ZZ4 cam is 208/221 .474/.510 112, I used this in my LT1 for s few years going a best of 13.2 at over 4200lbs with 3.42s 2800 stall and 28" slicks. Bet the heads will let you run 1.6s on this cam too and it should be CA emissions friendly.

There are a lot of options out there let us know is emissions is a concern and what the lift capacity is on those heads and I can keep going.

Depending on emissions concerns I don't think Dave's recommendation of up to 230 degrees is out of line. With my LT1 intake raising the powerband a few hundred RPMs and the extra pork of my car I am happy with the current mid 220s duration cam, it is tighter than 112 and I doubt it would pass emissions.

The ZZ4 cam is a good bit bigger yet completely well mannered and makes 355hp with L98 heads which flow 15% less than the Vortecs.

ZZ4 cam is 208/221 .474/.510 112, I used this in my LT1 for s few years going a best of 13.2 at over 4200lbs with 3.42s 2800 stall and 28" slicks. Bet the heads will let you run 1.6s on this cam too and it should be CA emissions friendly.

There are a lot of options out there let us know is emissions is a concern and what the lift capacity is on those heads and I can keep going.

Depending on emissions concerns I don't think Dave's recommendation of up to 230 degrees is out of line. With my LT1 intake raising the powerband a few hundred RPMs and the extra pork of my car I am happy with the current mid 220s duration cam, it is tighter than 112 and I doubt it would pass emissions.

The good thing is the truck and owner live in Oregon and have no emission tests.
I need off throttle response with a stock converter. I know he wants to stick with it. He is running a 700r4 at least!

I should have said STOCK CONVERTER on my original post! Sorry
The advice is good though!

The guys that speced my cam ask those specs remain confidential and I respect that request especially since I plan to do more buissiness with them in the future.

I ran the ZZ4 cam with 1650 stall and 2.93s drove just fine even in my whale of a car. Like I said before too need to consider the LT1 intake shift the powerband up costing some torque and the car is a whale.

I would be interested to see ZZ4 with 1.6s, would try to get some compression, probably can't run the 11.5 I am but bet you can approach 10:1. That is what the iron head LT1s were with a 191/196 .41x/.42x cam cranking 200psi and tuned for 87 octane. Not sure how much of the compression tolerance on these beasts is the cooling and how much is the chamber but I am sure it is a bit of both.

The more I think about it I think with the Ramjet cam with a long runner intake would be an almost unmanagable torque monster in that light truck.

If you want to try something like the Ramjet cam I have a couple stock b-body LT1 cams needlessly collecting dust in my garage, just a tad smaller than the Ramjet cam.

Depending on emissions concerns I don't think Dave's recommendation of up to 230 degrees is out of line. With my LT1 intake raising the powerband a few hundred RPMs and the extra pork of my car I am happy with the current mid 220s duration cam, it is tighter than 112 and I doubt it would pass emissions.

as long as the tune is correct to pass emissions (not in full race form) and you have a good set of cats, passing emissions is not as difficult as most people think. of course it will have no power when tuned for emiss but the sticker is what counts at that point. depending on what part of the 5-gas is out of limits, you can usually adjust to compensate. its just a matter of knowing what to "tweak". besides, the emissions "standard" is different from vehicle to vehicle and depends on the year._________________

I tend to think of things from the factory injection standpoint with O2s in the mix though even there they can be turned off, but with them interfering it complicates passing a sniffer with the currently popular cams any larger than mid-220s.
I know good cats can do a lot too clean up exhaust, pumping fresh air in too dilute is another good trick etc. Just recently on the LT1s there is a STRONG tendancy to get back too the overlap from the days of old. People are realizing the pcm can deal with it just fine.
I think the guy is going too far but there is one guys selling a lot of cams for LT1s down in the 107-108 LSA range, some of the owners are finding them VERY exhaust sensitive though.
Suprizing number of guys running .600 on the street too and endup wondering what the highend miss is after a few months or a year.

Our FI engines, either MAF or Speed Density, are sensitive to LSA. Everything I've read and from posts on other Forums pretty much fixes 112 as a tight as you should go on a FI street engine.

Once you go below 112, overlap becomes much more difficult to tune in the ECM/PCM and it also raises but narrows the torque band. No impossible, but it's just calls for more tweaking. 112 or wider will slightly lower the torque peak but it'll be much broader.

One other factor that is seldom discussed are the cam's ramps.

From my personal experience, for a street engine, you want the most aggressive intake ramps with slightly less aggressive exhaust ramps.

Aggressive intake ramps allow the intake valve to open quicker, allowing flow to being sooner BUT without the need for longer duration to get the same flow. This is GREAT for a street engine, but not so for a high RPM pure racer. As the RPMs climb over 6000 or so, the aggressive ramp cams make the valves more difficult to control.

Slightly Less aggressive exhaust ramps allows the exhaust valve to set down more gently, thus preventing that valve from bouncing off the seat. So this allows you to use LESS spring pressure to control the valves. This is good since you only want to use the minimum amount of spring that'll do the job.

If you want to compare ramps, grab one of your catalogs, say CompCams (the ONLY aftermarket cam I'll run) and find two that have the same .050 duration specs. Say, 224/230 @ .050 and make sure the advertised duration is measured at the same point, say .006

Now subtract the .050 duration from the advertised duration. The smaller the difference the more aggressive the ramps.

Don't forget valve lift either. You want lots of lift.

CompCams has one intake lobe with 224 intake duration at .050 and it'll give you .603 valve lift with a 1.6; .57x with a 1.5 Even if your heads have max flow at .500, raising the valve to, say, .570 allows max flow for a longer period of time. It's NOT wasted lift as some think.

Using the specs above, the only reason not to raise the valve to .570 is if your heads show backflow or port stall anywhere between .500 and .570. If that happens, you'll need to head to the cylinder head store for some different ones.

BTW, I wouldn't go more than 224 @ .050 on a 350 street engine if driveability and emissions are in the picture. I'd also go with a 114 LSA. For me, 218/224 is a better choice for a 350. Your mileage may vary. LOL

Like I said above I know someone is specing at least as low as 107 in LT1s these days, mine is not that tight but is tighter than 112 and it seems to work just fine all with the stock computer.

You need to read fewer magazines and find out more about cars that actually perform. What people say you need and what actually work are often two entirely different things.

I know you are well intentioned but almost your whole post is outdated theory that is just plain WRONG. The guys who make the 114LSA mistake are wondering why their strokers are slower than my stock shortblock .

You want to pretend to know anything please post YOUR RESULTS.
I get REALLY tired of kids who read a magazine once handing out info especially when it contradicts the info given by someone with PROOF.

You cannot post new topics in this forumYou cannot reply to topics in this forumYou cannot edit your posts in this forumYou cannot delete your posts in this forumYou cannot vote in polls in this forumYou cannot attach files in this forumYou can download files in this forum